When a stimulus is applied on axonal membrane then generation of action potential is due to

Answer

### Step-by-Step Solution:

1. **Understanding Neuron Structure**:
- Neurons are specialized cells that transmit nerve impulses. They have a polarized membrane at rest, meaning there is a difference in charge across the membrane.

2. **Resting Potential**:
- At resting potential, the axonal membrane is polarized due to the activity of ion channels. Specifically, sodium (Na⁺) ions are pumped out of the neuron while potassium (K⁺) ions are pumped in, resulting in a negative charge inside the neuron compared to the outside.

3. **Ion Permeability**:
- The axonal membrane is more permeable to potassium ions than to sodium ions at rest. This allows K⁺ to move out of the neuron more easily than Na⁺ can enter, maintaining the negative internal charge.

4. **Stimulus Application**:
- When a stimulus is applied to the axonal membrane, it causes a change in the membrane's permeability. This leads to a sudden influx of sodium ions into the neuron.

5. **Generation of Action Potential**:
- The influx of Na⁺ ions causes the inside of the axonal membrane to become positively charged relative to the outside, reversing the polarity of the membrane. This rapid change in charge is known as depolarization and is the basis for the generation of an action potential.

6. **Conclusion**:
- Therefore, the generation of action potential upon stimulus application is due to the sudden influx of sodium ions into the axonal membrane and the resultant change in polarity.

### Final Answer:
The generation of action potential when a stimulus is applied on the axonal membrane is due to the sudden influx of sodium ions into the axonal membrane, leading to a change in polarity.

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